1. Field of the Invention
The present invention relates to a liquid processing apparatus and a liquid processing method for applying a predetermined liquid processing to a substrate such as a semiconductor wafer.
2. Description of the Related Art
In the manufacturing process of a semiconductor device, a liquid processing apparatus is used for processing a semiconductor wafer (wafer) with a process solution such as a chemical solution or pure water so as to remove contaminants such as particles, organic contaminants and metal impurities from the wafer and for applying an etching treatment to the wafer.
With a prominent progress achieved in recent years in the miniaturization, degree of integration and mass production of semiconductor devices, the wafer size is increased from 200 mm ø (8 inches) to 300 mm ø (12 inches). As a result, the weight of the wafer itself is increased, and the carrier (container) housing the wafers is rendered bulky and heavy. For storing and transferring wafers of 300 mm ø, used is a carrier horizontally housing, for example, 25 wafers a predetermined distance apart from each other. On the other hand, concerning the liquid processing of the wafer, it is desirable in terms of the productivity to process simultaneously as large number of wafers as possible. Such being the situation, employed is a method of processing, for example, 50 wafers in a single operation.
For subjecting 50 wafers of 300 mm ø to a liquid processing, it is necessary to transfer the wafers housed in two carriers into a liquid processing apparatus. For example, 25 wafers housed substantially horizontal in a single carrier are taken out by using a wafer delivery device so as to be delivered to a posture changing device within the liquid processing apparatus. Then, additional 25 wafers housed in another carrier are delivered to the posture changing device by using the wafer delivery device. In the posture changing device, a total of 50 wafers are collectively changed from the horizontal posture into the vertical posture, and the 50 wafers that are held vertical are delivered to the wafer transfer device so as to be transferred into a liquid processing section. A predetermined liquid processing or a drying processing is applied to the wafers in the liquid processing section. After the liquid processing, the wafers are brought back to the two vacant carriers such that 25 wafers are housed in each of these vacant carriers by the procedures opposite to those in the process of transferring the wafers into the liquid processing sections.
However, a difficulty is brought about in the case where the wafers housed in two carriers are subjected to a liquid processing as a single lot. Specifically, where the predetermined number of wafers are not housed in the second carrier, though the wafers housed in the first carrier are transferred into the posture changing device without any problem, it is necessary for the wafers transferred previously into the posture changing device not to be subjected to the liquid processing and to be returned again from the posture changing device to the carrier for starting the processing for another lot, giving rise to the problem in respect of the loss of the liquid processing time.
It should also be noted that, where the wafers are transferred into and out of the carrier through a single position, it is necessary to move the vacant carrier, from which the wafers have been taken out, to a predetermined site and, then, to transfer another carrier housing the wafers to the wafer transfer site. Since a predetermined time is required for the carrier transfer, another problem is generated that the through-put is lowered.
What should also be noted is that, where the wafers are taken out of the carrier, in which the wafers are housed substantially horizontal, by using a wafer delivery device so as to be delivered to the posture changing device and, then, the wafers are delivered to a wafer transfer device for transferring into the liquid processing section or where the wafers are transferred in the opposite route, the number of required mechanisms is increased so as to increase the arranging area and, thus, to the problem of an enlarge footprint of the apparatus.